1. Technical Field
The present invention relates to a semiconductor device including a semiconductor module in which a semiconductor chip and a heat sink are sealed by a resin to form an integrated structure, the semiconductor chip in which a semiconductor power element is formed of which heat radiation is performed by the heat sink. The present invention is suitably applied to a semiconductor device including a semiconductor module having, for example, a two-in-one structure in which two semiconductor power elements of an upper arm (high-side element) and a lower arm (low-side element) are sealed in a single resin sealing section.
2. Description of the Related Art
Conventionally, a semiconductor module has been disclosed that has a two-in-one structure in which an upper arm and a lower arm, each including a semiconductor power element, are connected in series. A semiconductor module disclosed, for example, in JP-B-4192396 includes insulated-gate bipolar transistors (IGBT) as the semiconductor power elements. The semiconductor module has a structure in which, in each of the upper arm and the lower arm, a heat sink is disposed with a copper block therebetween on an emitter side of a semiconductor chip in which the IGBT is formed, and a heat sink is disposed on a collector side thereof. The structure is then sealed by resin in a state in which each heat sink is exposed from a resin sealing section.
A semiconductor module having a structure such as that described above is joined to, for example, a cooling mechanism having a coolant passage through which a coolant passes. As a result, the semiconductor module can be cooled with high cooling capability. At this time, the upper arm and the lower arm are disposed in alignment on the upstream side and the downstream side of the coolant flow in the conventional semiconductor module, and thermal resistances of the heat sinks included in each arm are almost the same. Therefore, a phenomenon occurs in which the temperature of the coolant increases because of heat from the semiconductor power element disposed on the upstream side of the coolant flow, and the cooling capability on the downstream side becomes lower than that on the upstream side, thereby raising the temperature of the semiconductor power element disposed on the downstream side to become higher than that of the semiconductor power element disposed on the upstream side.
Therefore, thermal design is restricted by the semiconductor power element on the downstream side in which temperature rise occurs. As a result, alleviation of the above-described phenomenon and more effective cooling of the semiconductor power element disposed on the downstream side are desired.